Rhizome Tips Research Articles

Identification of LsPIN1 gene and its potential functions in rhizome turning of Leymus secalinus

BackgroundContinuous tilling and the lateral growth of rhizomes confer rhizomatous grasses with the unique ability to laterally expand, migrate and resist disturbances. They play key roles especially in degraded grasslands, deserts, sand dunes, and other fragile ecological system. The rhizomatous plant Leymus secalinus has both rhizome buds and tiller buds that grow horizontally and upward at the ends of rhizome differentiation and elongation, respectively. The mechanisms of rhizome formation and differentiation in L. secalinus have not yet been clarified.ResultsIn this study, we found that the content of gibberellin A3 (GA3) and indole-3-acetic acid (IAA) were significantly higher in upward rhizome tips than in horizontal rhizome tips; by contrast, the content of methyl jasmonate and brassinolide were significantly higher in horizontal rhizome tips than in upward rhizome tips. GA3 and IAA could stimulate the formation and turning of rhizomes. An auxin efflux carrier gene, LsPIN1, was identified from L. secalinus based on previous transcriptome data. The conserved domains of LsPIN1 and the relationship of LsPIN1 with PIN1 genes from other plants were analyzed. Subcellular localization analysis revealed that LsPIN1 was localized to the plasma membrane. The length of the primary roots (PRs) and the number of lateral roots (LRs) were higher in Arabidopsis thaliana plants overexpressing LsPIN1 than in wild-type (Col-0) plants. Auxin transport was altered and the gravitropic response and phototropic response were stronger in 35S:LsPIN1 transgenic plants compared with Col-0 plants. It also promoted auxin accumulation in root tips.ConclusionOur findings indicated that LsPIN1 plays key roles in auxin transport and root development. Generally, our results provide new insights into the regulatory mechanisms underlying rhizome development in L. secalinus.

Tissue-Specific Transcriptomic Profiling of Sorghum propinquum using a Rice Genome Array

Sorghum (Sorghum bicolor) is one of the world's most important cereal crops. S. propinquum is a perennial wild relative of S. bicolor with well-developed rhizomes. Functional genomics analysis of S. propinquum, especially with respect to molecular mechanisms related to rhizome growth and development, can contribute to the development of more sustainable grain, forage, and bioenergy cropping systems. In this study, we used a whole rice genome oligonucleotide microarray to obtain tissue-specific gene expression profiles of S. propinquum with special emphasis on rhizome development. A total of 548 tissue-enriched genes were detected, including 31 and 114 unique genes that were expressed predominantly in the rhizome tips (RT) and internodes (RI), respectively. Further GO analysis indicated that the functions of these tissue-enriched genes corresponded to their characteristic biological processes. A few distinct cis-elements, including ABA-responsive RY repeat CATGCA, sugar-repressive TTATCC, and GA-responsive TAACAA, were found to be prevalent in RT-enriched genes, implying an important role in rhizome growth and development. Comprehensive comparative analysis of these rhizome-enriched genes and rhizome-specific genes previously identified in Oryza longistaminata and S. propinquum indicated that phytohormones, including ABA, GA, and SA, are key regulators of gene expression during rhizome development. Co-localization of rhizome-enriched genes with rhizome-related QTLs in rice and sorghum generated functional candidates for future cloning of genes associated with rhizome growth and development.

Analysis of ESTs from a Normalized cDNA Library of the Rhizome Tip of Oryza longistaminata

Oryza longistaminata, a perennial wild rice species with an AA genome, is characterized by the presence of rhizomatous stems. The rhizomatous trait in rice was previously shown to be quantitatively controlled by many genes, but the molecular mechanism related to rhizome development is still unknown. In the present study, expressed sequence tags (ESTs) generated from rhizome tips of O. longistaminata were collected and analyzed. A total of 10,283 complimentary deoxyribunucleic acid clones were randomly sequenced, which generated 10,136 raw sequences, and finally, 4,419 unisequences with diverse functional categories were generated. These unisequences were mapped onto the Oryza sativa genome, which revealed that 4,285 (96.97%) and 4,151 (93.94%) of the unisequences were alignable to the japonica and indica genomic sequences, respectively, with >80% sequence identity. Additionally, 41 unisequences showed four typical types of alternative splicing patterns. More than 600 simple sequence repeats were identified in these unisequences. A subset of unisequences were physically colocalized onto rhizome-related quantitative trait locus intervals in rice and sorghum, and one gene, OLRR1, was further confirmed to be enriched in the rhizome tip and young leaf by real-time polymerase chain reaction and in situ hybridization. Unisequences reported in this study provide valuable data for molecular dissection of the rhizomatous growth habit in O. longistaminata.

Identification of rhizome-specific genes by genome-wide differential expression analysis in Oryza longistaminata.

BackgroundRhizomatousness is a key component of perenniality of many grasses that contribute to competitiveness and invasiveness of many noxious grass weeds, but can potentially be used to develop perennial cereal crops for sustainable farmers in hilly areas of tropical Asia. Oryza longistaminata, a perennial wild rice with strong rhizomes, has been used as the model species for genetic and molecular dissection of rhizome development and in breeding efforts to transfer rhizome-related traits into annual rice species. In this study, an effort was taken to get insights into the genes and molecular mechanisms underlying the rhizomatous trait in O. longistaminata by comparative analysis of the genome-wide tissue-specific gene expression patterns of five different tissues of O. longistaminata using the Affymetrix GeneChip Rice Genome Array.ResultsA total of 2,566 tissue-specific genes were identified in five different tissues of O. longistaminata, including 58 and 61 unique genes that were specifically expressed in the rhizome tips (RT) and internodes (RI), respectively. In addition, 162 genes were up-regulated and 261 genes were down-regulated in RT compared to the shoot tips. Six distinct cis-regulatory elements (CGACG, GCCGCC, GAGAC, AACGG, CATGCA, and TAAAG) were found to be significantly more abundant in the promoter regions of genes differentially expressed in RT than in the promoter regions of genes uniformly expressed in all other tissues. Many of the RT and/or RI specifically or differentially expressed genes were located in the QTL regions associated with rhizome expression, rhizome abundance and rhizome growth-related traits in O. longistaminata and thus are good candidate genes for these QTLs.ConclusionThe initiation and development of the rhizomatous trait in O. longistaminata are controlled by very complex gene networks involving several plant hormones and regulatory genes, different members of gene families showing tissue specificity and their regulated pathways. Auxin/IAA appears to act as a negative regulator in rhizome development, while GA acts as the activator in rhizome development. Co-localization of the genes specifically expressed in rhizome tips and rhizome internodes with the QTLs for rhizome traits identified a large set of candidate genes for rhizome initiation and development in rice for further confirmation.

Water integration patterns in two rhizomatous dune perennials of different clonal fragment size

In clonal plants, a clonal fragment is a basic unit. There may exist clonal integration that is often regarded adaptive. By definition, a larger clonal fragment comprises more interconnected ramets and/or occupies a larger area of the habitat. When the habitat is so heterogeneous in terms of essential resources that the resources the whole clonal fragment needs can be captured only in a limited number of microhabitats, a large clonal fragment may require extensive and/or intensive clonal integration. Therefore, we hypothesize that in an environment where the resources are distributed in a highly heterogeneous way, a species forming large clonal fragments possesses more extensive and/or intensive clonal integration gaining essential resources than that forming small ones. This hypothesis was tested in a field experiment with two rhizomatous species growing in inland-dune habitats with high heterogeneity of water resource, one ( Psammochloa villosa) forming large clonal fragments and the other ( Hedysarum laeve) forming small ones. In P. villosa, tracer-(water-soluble acid fuchsin)-labeled water could be transported along the rhizome at a velocity of about 0.93 m per hour and 4 ramets per hour, which was much faster than that in H. laeve. Similarly, the acid fuchsin-labeled water was transported to a longer length in the rhizomes (3.96 m vs. 1.12 m) and to more ramets (14 vs. 3) in P. villosa than in H. laeve. In P. villosa, the acid fuchsin-labeled water reached the ends of the rhizomes and all ramets along the rhizomes were dyed purple. In H. laeve, however, the acid fuchsin-labeled water could not reach the rhizome tips and along the rhizomes only some ramets were labeled. The results suggest that P. villosa is an extensive and intensive integrator, whereas H. laeve is a restrictive and less intensive integrator, supporting the hypothesis. The possible mechanisms and the ecological implications of the findings were discussed.

防水層に対する地下茎先端の押し付け力測定装置の開発と測定結果

The resistance of membranes to rhizome and root penetration is also important for green roof as well as the other performances for waterproofing. For suitably estimate membranes for this purpose, the actual penetrating force of them to membranes has to make clear. Using the inherent nature of them seeking and growing for moisture, the apparatus for measuring penetrating force was developed. Penetrating forces of rhizome tips of bamboo grass and lawn grass were measured from spring to summer. They increased in a few weeks with periodically swinging in day and night, and the maximum forces of 9.8N and 6N were observed respectively.

Uptake, transport and seasonal recycling of 134Cs applied experimentally to bracken ( Pteridium aquilinum L. Kuhn)

Solutions containing 134Cs were applied to cultivated clones of bracken. The radionuclide was taken up by roots, rhizome tips and leaf tips, and its subsequent retention and transport was monitored over a year. 134Cs was transported through growing plants, recycled down to rhizomes at the end of the growing season and concentrated in meristems and second generation leaves. Accidentally released 137Cs may therefore be taken up and recycled to succeeding generations of leaves in this important component of extensive upland and heathland ecosystems. The long-lived nature of bracken means that 137Cs could remain environmentally available for many years longer than its physical half-life (30.2 yrs) and concentration in meristems could potentially cause genetic and phenotypic change in clones.

In VitroPropagation ofPodophyllum peltatum

The lignan podophyllotoxin, occurring in Podophyllum emodi Wall, ex Royale and Podophyllum peltatum. L., is the starting compound for the semi-synthesis of the anticancer drugs etoposide and teniposide. In this study, we evaluate development of an in vitro propagation protocol to rapidly produce high yielding Podophyllum peltatum plants. Rhizome tips were inoculated on MS medium supplied with 4.4 microM N(6)-benzyladenine and 0.025% (w/v) activated charcoal. These explants formed terminal buds, similar to the ones found in nature. These buds were sources of in vitro bud cultures. These bud cultures were classified as: apical, axillary, and adventitious and the effects of various N(6)-benzyladenine concentrations on the three types of bud cultures were evaluated through bud, leaf, and root inductions. Cultures of axillary and adventitious buds were more proliferous for bud induction. Podophyllotoxin contents of in vitro rooted bud and plantlet cultures were similar to the content found in the wild. Plantlets and buds were acclimatized under controlled environment conditions.

Reproductive potential of caucasian clover at four locations within New Zealand

Seedlings of KZ2 caucasian clover (Trifolium ambiguum) were grown at 4 sites within New Zealand (Kerikeri 36°S, Palmerston North 40°S, Lincoln 43°S and Gore 46°S) where they received natural daylight and temperatures during 1997. Northernmost plants produced more vegetative primary crown shoot buds than southernmost. In the first growing season numbers of flowering shoots formed per plant were: K 17.9, P 10.0, L 10.2 and G 5.7. In spring of the second growing season, mean numbers of primary crown flowering shoots per plant at peak flowering in December 1997 were: K 19, P 30, L 55, G 20. Fewer flowering shoots formed at upturned rhizome tips. Daylength was not the major factor controlling flowering, the results instead supporting the hypothesis that low temperatures provided the main flowering stimulus. Lincoln was the best of the four locations overall for flowering shoot production. Fewer flowering shoots at Gore probably resulted from slower growth in cooler conditions. Poorer flowering at Kerikeri in the second season might have resulted from the warmer northern winter or been linked to the overproduction of vegetative buds in the first season. Stronger flowering at Kerikeri during the first season raises the possibility, though, of growing caucasian clover as an annual crop for seed production in Northland if sown early in spring. Keywords: caucasian clover, daylength, flowering, low temperature, seed production, Trifolium ambiguum

Chronic Toxicity of Atrazine to Sago Pondweed at a Range of Salinities: Implications for Criteria Development and Ecological Risk

The objective of this study was to conduct a series of 28-d partial life-cycle atrazine subchronic toxicity tests with sago pondweed, Potamogeton pectinatus, at salinities of 1, 6, and 12 ppt. These data will be used for development of a chronic estuarine criterion for atrazine in Maryland waters of Chesapeake Bay and to determine possible ecological risk for a sensitive nontarget species. The three endpoints used for this submerged aquatic macrophyte were final wet weight, final dry weight, and final number of rhizome tips at the termination of the 28-d test. Dry weight was determined to be the most sensitive endpoint. Chronic values from a one-way ANOVA using dry weight were 21.2, 21.2, and 10.6 μg/L at salinities of 1, 6, and 12 ppt, respectively. Chronic values using wet weight were 21.2 μg/L at all three salinities. A chronic value of 94.9 μg/L was reported at all three salinities using rhizome tips as the endpoint. A two-way ANOVA was also used for analysis of data to increase the power of detecting differences among treatments and assess salinity interaction. The salinity effects were averaged in the two-way ANOVA. Both rhizome tips and dry weight were used in the two-way ANOVA; wet weight did not satisfy the equal variance assumption. The chronic value for rhizome tips was 94.9 μg/L atrazine, which is the same value reported from the one-way ANOVA. There was no salinity effect and no interaction between salinity and atrazine concentration. The chronic value determined from the two-way ANOVA using dry weight was 5.3 μg/L; there was a salinity effect but no significant salinity/atrazine concentration interaction. Salinity was not reported to effect either dry weight or rhizome tips after 28-d exposures in the controls but wet weight was significantly lower at 12 ppt when compared with 1 and 6 ppt. Ecological risk to sago pondweed from atrazine exposure was judged to be low based on recent exposure data from the mainstem, tributaries, and streams in Chesapeake Bay.

Seasonal Pattern of Leaf Growth and Senescence of Nardus stricta and Responses of Tussocks to Differing Severity, Timing and Frequency of Defoliation

1. A field study of the seasonal growth of Nardus stricta showed that leaf turnover was slow, averaging 2.5 leaves per tiller over the growing season. Periods of lamina extension growth and senescence were generally separated in time; fastest growth, at 4-5 mm per tiller per day, occurred in June July and the senescence rate was low until early autumn when it rose to 6 mm per tiller per day. Sheathing tiller bases, already well developed in May, increased in weight by 27% between May and October; total water-soluble carbohydrate (TWSC) concentration increased by 150% (from 75 to over 165 g per kg dry weight) while N, P and K concentrations declined over this period. 2. A pot study showed that the age class of inter-connected tillers on rhizome tips greatly influenced growth; mean rates of lamina extension and production of daughter tillers were higher in younger tillers while the likelihood of flowering was greater for older (3-4 leaf) tillers. The pattern of growth provided evidence for acropetal movement of assimilate. 3. Field cutting experiments showed that Nardus was relatively insensitive to defoliation in the short term. Removal of 50% or 100% of the length of the leaf lamina in June only, July only or in both June and July resulted in a temporary reduction in lamina extension rate per tiller but did not significantly affect the weight of leaf produced in the first season. There was a non-significant trend for the size of tiller base to be reduced as the severity of cutting was increased. Concentrations of TWSC and N,P, and K in tiller bases showed no variation attributable to cutting. 4. In a long-term cutting experiment lasting 4 years, Nardus was cut so as to leave 1, 4 or 8 cm of lamina in June only, July only, or in June and July. Two seasons elapsed before lamina extension was reduced on cut plants. The weights of clippings were greatly reduced over successive years when tillers were cut to leave only 1 cm oflamina but were little affected when 8 cm of lamina remained, with the 4-cm treatment intermediate; the reduction was greatest with plants cut in both June and July and least with plants cut in June only with those cut only in July being intermediate. 5. Tussock biomass, assessed after 4 years of cutting and a season of uninterrupted growth, was decreased as the height of cut was reduced and by repeated cutting; timing (June compared with July) was unimportant. Both tiller numbers and mean weight per tiller were reduced. Flowering vigour was increased by cutting. Timing was important, with plants cut in July only or in both June and July having more flowers than those cut in June only. The amounts of TWSC and N, P and K reserves were reduced by cutting with reduction in tiller base size being more important than effects on concentration. 6. In a comparative field study, the rate of lamina extension in Nardus averaged less than half that of Agrostis capillaris or A. canina growing in the same sward. This underlines the importance of selective grazing as an influence on species balance in acid grasslands.

Ultrastructural specializations of the cell wall sleeve around plasmodesmata

Specialized structures were observed in the sleeve of wall surrounding plasmodesmata in the rhizome tips of Nephrolepis exaltata and root tips of Spirodela oligorrhiza, Azolla pinnata, and Hordeum vulgare. Material was prepared either by fixation in glutaraldehyde/paraformaldehyde/tannic acid followed by cell wall digestion, or by rapid freezing and freeze substitution, prior to resin embedding. Two structures were identified: rings of electron‐opaque material encircling the neck region of plasmodesmata and electron‐opaque helices spiraling around the length of plasmodesmata. In some instances, particle‐like subunits were observed in the electron‐opaque rings. The possible role of these structures as external sphincters involved in the control of permeability of plasmodesmata is discussed.

In vitro establishment and multiplication of Nymphaea hybrid ?James Brydon?

Rhizome tips were the most suitable explants for in vitro plant regeneration and multiplication of Nymphaea hybrid ‘James Brydon’ on Murashige and Skoog medium containing different concentrations and combinations of indole-3-acetic acid, 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid, 6-benzyladenine (BA), kinetin, 2-isopentenyladenine (2iP) and gibberellic acid (GA3). A combination of 2iP, BA, and NAA strongly favored induction of shoot buds and shoot proliferation. Pretreatment of shoot cultures at 8°C for 30 days or with 14.4 or 28.9 μM GA3 for 15 days did not improve shoot multiplication. A 16-h photoperiod with photosynthetic photon flux of 30 μmol m-2 s-1 was found to be the optimum light condition for shoot growth and multiplication. Multiple shoots produced well developed root systems within 4 weeks after transfer to a plant growth regulator-free medium containing activated charcoal.

Virus elimination by meristem-tip culture from a range of Alstroemeria cultivars

A technique for virus elimination by meristem culture was developed for a range ofAlstroemeria cultivars. Meristems were excised from the rhizome tips and placed on a medium with indole-3-butyric acid, the required concentration of which was cultivar dependent: Six to eight weeks after dissection a shoot had formed which was transferred to a medium without growth regulators. On filter paper bridges, in a liquid medium, root formation was better than on a solid medium. In many cases a new rhizome developed. If not, the plantlet eventually died. Transfer into soil was more successful with the plantlets rooted in liquid medium than with those rooted in solid medium. Virus elimination was cultivar dependent, but in most cultivars plants resulting negatively in serological tests could be obtained. After repeated testing and selection for horticultural properties these plants may be used to start high quality mother plots.

In vitro propagation of Alstroemeria ?Alsaan?

Plantlets were regenerated from Alstroemeria ‘Alsaan’ rhizome tips cultured in vitro on solid and liquid media based on Murashige and Skoog salt formulation. The quality of the cultures was superior when intact rather than longitudinally sliced rhizome tips were used as explants and when a temperature of 8°C rather than 22°C was used at the initiation stage. More roots were produced on rhizome tips containing a rhizome apical meristem than on rhizome sections lacking such a meristem. Most (90%) of the rooted plantlets were successfully acclimatized and developed into true-to-type flowering plants.

Tillage Effects and Environmental Influences on Quackgrass (Agropyron repens) Rhizome Growth

Field experiments were established in 1978 and repeated in 1979 to monitor quackgrass [Agropyron repens (L.) Beauv. ♯3 AGRRE] rhizome growth through a growing season. Quackgrass shoots grew most vigorously when temperatures were moderate. They elongated and differentiated an inflorescence in June. Rhizome apical tips remained belowground in late spring, early summer, and early fall. Quackgrass rhizome tips grew vertically and emerged from the soil in midsummer and late fall. Experiments conducted in growth chambers revealed that photoperiod, temperature, and nitrogen level affected quackgrass shoot and rhizome growth. Shoots grew vigorously at 21C and elongated to differentiate an inflorescence when exposed to a photoperiod of 14 h or longer. Rhizome apical tips remained belowground when plants were grown at 21 C and received 16 or 12 h of light, but the tips curved upward and emerged from the soil when quackgrass was grown at 32 or 10 C, or when the plants received 14 or less than 10 h of light. The temperature and photoperiod responses coordinated to partition the growing season into primary rhizome and rhizome-tiller growth periods.

Accumulation of amyloplasts on the bottom of normal and inverted rhizome tips of Caulerpa prolifera (Forssk�l) Lamouroux

Caulerpa prolifera (Chlorophyta) exhibits a gravimorphogenetic response to inversion by switching the site of new rhizoid initiations to correspond with the new direction of the gravity stimulus. When plants were fixed at 6 and 24 h after being held in either a normal or an inverted position the switch in the site of organ differentiation, upon inversion, was found to be preceded by the accumulation of starch-containing amyloplasts on the bottom of the rhizome. Approximately 1.5-2.0 times as many amyloplasts were found at the bottom of normal or inverted rhizomes as compared with the top in a region extending from 200 to 1,000 μm behind the rhizome tip. All new rhizoid initials were located in the region of amyloplast accumulation and each rhizoid initial contained numerous amyloplasts.

C-Glycosylxanthones in Diploid and Tissue Culture-Induced Autotetraploid Davallia fejeensis

Rhizome tips (about 2 cm long) of diploid Davallia fejeensis were collected in the Enid A. Haupt Conservatory of the New York Botanical Garden, cleaned, rinsed in tap water and further trimmed. Voucher specimens are at NY. Explants (6-8 mm long) were cultured on 1% agar-gelled sterile nutrient medium of Knudson as modified by Steeves et al. (1955) and supplemented with 2% sucrose in order to provide control diploid sporophytes growing in axenic culture. Roots, leaves, and rhizomes of the resulting plants were excised and induced to differentiate into aposporous diploid gametophytes. Stock cultures of diploid gametophytes were multiplied and further grown on liquid media supplemented with 0.6% agar to effect fertilization and raise tetraploid sporophytes. Tetraploid gametophytes were isolated from this tissue culture-induced tetraploid material by repeating the procedure followed at the diploid level. In this way, both diploid and tetraploid sporophytes and gametophytes were made available for this study. Phenolic compounds were isolated by two-dimensional paper chromatography of an 80% methanol extract of green material in t-BuOH-HOAc-H20, 3:1:1 (TBA) and 15% aqueous acetic acid (HOAc), followed by one-dimensional paper chromatography in water. C-glycosylxanthones appeared as orange compounds in ultraviolet light and turned yellow when fumed with ammonia. Both purified compounds were co-chromatographed with mangiferin and isomangiferin isolated from Asplenium montanum Willd. (Bozeman & Radford 11552, NY). Rf values in TBA, BAW, HOAc, and H20 were: mangiferin, 0.31, 0.43, 0.43, 0.12; isomangiferin, 0.19, 0.29, 0.23, 0.04; Asplenium mangiferin, 0.34, 0.42, 0.42, 0.11; Asplenium isomangiferin, 0.21, 0.32, 0.23, 0.03; and rutin standard, 0.43, 0.45, 0.56, 0.25. The BAW and HOAc values are very similar to those of Smith and Harborne (1971), but the TBA and HOAc values differ from those of Markham and Wallace (1980). Absorption spectra (MeOH, nm) were: mangiferin, 232, 260, 270sh, 310, 364; isomangiferin, 240, 258, 270sh, 312, 365. The compounds were unaffected by acid hydrolysis (1 hr, 2N HC1, 100?C).

Fine structure study on the development of trabeculae in the siphonous green algaCaulerpa simpliciuscula C. Ag.

Bundles of fibrils and tubular structures were found to be associated with growing trabeculae ofCaulerpa simpliciuscula. In the rhizome tips, the bundles had an average diameter of 0.1 to 0.3 μm, and a length greater than 10 μm. The fibrils in the bundles were oriented in a strictly parallel fashion, with an individual thickness of 3–8 nm. The development of trabeculae started with the apposition of material of low electron density onto the bundles, which in this way became the inner skeleton of the trabeculae.

Metabolic activity, adenosine phosphates and energy charge of below ground biomass of Juncus roemerianus Scheele and Spartina alterniflora Loisel

Anaerobic metabolism of different below ground plant parts of J. roemerianus and S. alterniflora in terms of dehydrogenase activity was significantly correlated with concentrations of adenosine triphosphate but not with energy charge. Energy charge was quite stable, ranging from 0·62 to 0·67 (mean 0·65) for S. alterniflora and 0·50 to 0·87 (mean of 0·69) for J. roemerianus. J. roemerianus rhizome tips were the most metabolically active tissue, followed by the buried colorless stem base and rhizome mid-section. Dead-looking rhizomes had some dehydrogenase activity. Roots of different sizes and rhizome bark were metabolically inert. Below ground stem base of S. alterniflora showed the same level of activity as J. roemerianus stem base. S. alterniflora rhizomes, however, showed at least an order of magnitude less activity than that of J. roemerianus.